TULSA (CN) – A white volunteer sheriff’s deputy who shot an unarmed black man to death after mistaking his own gun for a Taser was charged Monday with second-degree manslaughter. Robert C. Bates, 73, an insurance agent and volunteer reserve deputy with the Tulsa County Sheriff’s Department, was charged with second-degree manslaughter involving culpable negligence. According to video evidence , Bates killed Eric Courtney Harris, 44, on April 2. In the video released by the sheriff’s office on Friday, Harris is shown running away from deputies as they pull up to his vehicle. He is chased down and held to the ground and a single gunshot is heard. Bates immediately apologizes as Harris screams that he has been shot. As Bates lies on the ground screaming that he is losing his breath, an officer says, “Fuck your breath.” Deputies were arresting Harris as part of an undercover investigation into illegal gun sales, according to media reports. Release of the video, coming so soon after the release of a video showing a white police officer shooting an unarmed black man to death in North Charleston, S.C., put U.S. policing tactics in world headlines again. “Oklahoma law defines culpable negligence as ‘the omission to do something which a reasonably careful person would do, or the lack of the usual ordinary care and caution in the performance of an act usually and ordinarily exercised by a person under similar circumstances and conditions,'” Tulsa County District Attorney Steve Kunzweiler said in a statement. If convicted, Bates faces up to 4 years in state prison. Bates was named Tulsa County’s Reserve Deputy of the Year in 2011. Tulsa County Sheriff Stanley Glanz told The Tulsa World that Bates is an “old friend” who “made an error.” Wealthy donors are among the office’s 130 reserve deputies, the sheriff’s office said last week. Bates donated several vehicles, guns and stun guns since he became a reserve deputy in 2008. Glanz brought in Tulsa Police Sgt. Jim Clark to investigate the shooting. Clark excused Bates’ actions as “slip and capture.” He said that in high-stress situations, a person who intends to do one thing may do something else. “These are mistakes that are made when you think you are doing one thing but you actually are doing another, and the result often is directly opposite of what you intended,” Clark said. “In effect, your intended behavior slips off the path that you want it to go because it is captured by a stronger response and sent to a different direction.” Bates was not conscious “of this unfortunate switch” until after he shot Harris, Clark said. “In his urgency, his concentration was focused exclusively on Harris’ back, where he intended to place the Taser darts,” Clark said. “Because of what’s called ‘inattentional blindness,’ meaning that he was not consciously paying attention to and registering it, he would not have been aware that the feel of the gun was different from that of the Taser. And in this case the weight of the gun and Taser are nearly identical.” Harris’ brother, Andre Harris, said Monday that his brother “was nonviolent, he was peaceful, he was loving, he was caring. He was my brother that I’ll never see again until I see him in heaven.” He accused authorities of trying to dissuade him from hiring an attorney. Bates could not be reached for comment Monday evening.